Preoperative Ultrasound-based Protocol for Optimization of Fluid Therapy to Prevent Early Intraoperative Hypotension

Preoperative Ultrasound-based Protocol for Optimization of Fluid Therapy to Prevent Hypotension Associated to General Anesthesia: a Randomized Controlled Trial

Background: Intraoperative hypotension increases 30-day mortality and the risks of myocardial injury and acute renal failure. Patients with inadequate volume reserve before the induction of anesthesia are highly exposed. The identification of latent hypovolemia is therefore crucial. Ultrasonographic measurement of the inferior vena cava collapsibility index (IVCCI) is able to detect volume responsiveness in circulatory shock and growing evidence support the theory that higher IVCCI can predict intraoperative hypotension.

The aim of the present study is to evaluate the potential benefit of an ultrasound-based protocol for preoperative fluid optimization. The investigators will perform a randomized-controlled study involving elective surgical patients. An ultrasound-based protocol (USP) arm and a conventional fluid therapy group (CFT) are to be formed. Ultrasound examinations will be performed twice in both groups: 2 hours and 30 minutes preoperatively. The inferior vena cava and the anterior lung fields will be scanned. In the USP group the participants will receive fluid therapy according to the ultrasonographic findings: high level of IVCCI and absence of signs of pulmonary edema will indicate fluid therapy. In the CFT group the attending anesthesiologist (blinded to the results of ultrasonography) will order fluid therapy on the basis of daily routine and clinical judgement.

The investigators will evaluate the incidence of intraoperative hypotension (primary outcome), postoperative metabolic status and organ functions and the amount of the administered intravenous fluids in both groups.

Study Overview

• Status: Completed
• Conditions: Hypotension; Anesthesia; Echocardiography; Perioperative Complication; Lung Ultrasound
• Intervention / Treatment: Procedure: Ultrasound-based protocol based fluid therapy

Detailed Description

A randomized-controlled study with 80 participants.

The investigators will use computer-generated unpaired random allocation method to an ultrasound-based protocol (USP) group or to the conventional fluid therapy (CFT) group.

Preoperative ultrasound examinations will be performed twice in both groups: 2 hours and 30 minutes preoperatively. The inferior vena cava and the lung fields (so called BLUE - Bedside Lung Ultrasound in Emergency - points: 2nd or 3rd intercostal space anterior, 5th-6th interspace anterior and posterior axillary line position) will be scanned. The collapsibility index (IVCCI) of the IVC is calculated, >40 percent is considered 'high IVCCI'. Lung ultrasound (LUS) is evaluated as indicative for 'lung congestion' if symmetric anterior B-profiles (at least 3 B-lines in anterior lung fields) are detected.

Baseline demographic (age, sex, height, weight) and comorbidity data (history of hypertension, chronic heart failure, coronary or cerebrovascular disease, respiratory illness e.g. COPD, past COVID, diabetes on insulin treatment) together with laboratory data (haemoglobin, creatinine, blood urea) are to be recorded.

A standardized practice of monitoring and induction of general anesthesia will allow for the detection of immediate and early (first 10 minutes of anesthesia) hypotensive events. A follow up for 24 hours is necessary for evaluating the fulfillment of secondary endpoints. A semi-quantitative lung ultrasound after 24 hours will estimate lung aeration.

• Study Type: Interventional
• Enrollment (Actual): 80
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Hungary
  • Budapest, Hungary, 1082
    • Semmelweis University, Deparment of Surgery, Transplantation and Gastroenterology

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

Elective surgery

• General surgical procedures
• Estimated duration of anesthesia > 60 minutes
• ASA class 2 or 3

Exclusion Criteria:

• Emergency procedure
• Reoperation, redo procedure
• Patient who is incapable of acting
• Uncontrolled hypotension (<90 mmHg)
• Uncontrolled hypertension (>180 mmHg)
• High risk valvular disease (Aortic Stenosis)
• Endocrine hypertension (Conn's syndrome, phaeochromocytoma)
• Sepsis (infection and SOFA≥2 pt)
• Conditions blocking lung ultrasound (pneumothorax without drainage, former pulmonary resection, pleural effusion affecting more than 2 interspaces)
• Pregnancy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ultrasound-based protocol group (USP); Preoperative intravenous (IV) fluid therapy is order according to the result of the preoperative ultrasound scans of the inferior vena cava and the lungs (2 hours and 30 minutes before surgery)	Procedure: Ultrasound-based protocol based fluid therapy; Protocol of the interventional group according to the ultrasonographic findings: Ultrasound scan 2 hours before surgery: IVCCI>40 percent and absence of symmetric anterior 'B-profile' on the lung ultrasound indicate intravenous (IV) fluid therapy: 8 ml/kg of isotonic, balanced crystalloid infusion. IVCCI≤40 percent AND/OR symmetric anterior 'B-profile' contraindicates further IV fluid therapy. A 2nd ultrasound scan at 30 minutes before surgery: IVCCI>40 percent and absence of symmetric anterior 'B-profile' on the lung ultrasound indicate further IV fluid therapy: 5 ml/kg of isotonic, balanced crystalloid infusion. IVCCI≤40 percent AND/OR symmetric anterior 'B-profile' contraindicates further IV fluid therapy.
No Intervention: Conventional fluid therapy; Preoperative IV fluid therapy (isotonic, balanced crystalloid infusion, if any) is determined by the discretion of the attending anesthesiologist.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rate of hypotension associated to general anesthesia induction	mean arterial pressure < 65 mmHg AND/OR ≥30 percent of decrease compared to baseline (before induction of anesthesia)	first 10 minutes of anesthesia

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dose of preoperative fluid therapy (in millilitres)	intravenous fluid therapy before anesthesia induction	preoperative time frame on the day of surgery
Dose fluid therapy of the operative day (in millilitres)	all intravenous fluid therapy on the day of surgery	24 hours
lactate level (mmol/l)	highest lactate level in mmol of an arterial blood sample	1st postoperative hour
base excess (mmol/l)	worst base excess level in mmol of an arterial blood sample	1st postoperative hour
urine output (millilitres/24 h)	summarized urine output after surgery	24 hours
lung ultrasound score (LUS)	Summarized lung ultrasound score of 12 fields of the thorax (0-36 pts)	24th postoperative hour

Collaborators and Investigators

• Sponsor: Semmelweis University
• Investigators: Principal Investigator: Sándor Soós, PhD, Semmelweis University, Department of Surgery, Transplantation and Gastroenterology

Publications and helpful links

General Publications

• Szabo M, Bozo A, Darvas K, Horvath A, Ivanyi ZD. Role of inferior vena cava collapsibility index in the prediction of hypotension associated with general anesthesia: an observational study. BMC Anesthesiol. 2019 Aug 7;19(1):139. doi: 10.1186/s12871-019-0809-4.
• Szabo M, Bozo A, Darvas K, Soos S, Ozse M, Ivanyi ZD. The role of ultrasonographic lung aeration score in the prediction of postoperative pulmonary complications: an observational study. BMC Anesthesiol. 2021 Jan 14;21(1):19. doi: 10.1186/s12871-021-01236-6.
• Bijker JB, van Klei WA, Vergouwe Y, Eleveld DJ, van Wolfswinkel L, Moons KG, Kalkman CJ. Intraoperative hypotension and 1-year mortality after noncardiac surgery. Anesthesiology. 2009 Dec;111(6):1217-26. doi: 10.1097/ALN.0b013e3181c14930.
• Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670. doi: 10.1378/chest.14-1313.
• Zhang J, Critchley LA. Inferior Vena Cava Ultrasonography before General Anesthesia Can Predict Hypotension after Induction. Anesthesiology. 2016 Mar;124(3):580-9. doi: 10.1097/ALN.0000000000001002.

Study record dates

Study Major Dates

• Study Start (Actual): December 15, 2021
• Primary Completion (Actual): August 29, 2022
• Study Completion (Actual): August 31, 2022

Study Registration Dates

• First Submitted: December 10, 2021
• First Submitted That Met QC Criteria: December 10, 2021
• First Posted (Actual): December 29, 2021

Study Record Updates

• Last Update Posted (Actual): September 7, 2022
• Last Update Submitted That Met QC Criteria: September 3, 2022
• Last Verified: September 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypotension
• Other Study ID Numbers: PUSPO

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No